1. Field of the Invention
The present invention relates to mass measuring units of the type that determine mass by noting changes in the resonant frequency of an oscillating mechanical system as a result of adding the mass to be measured to the oscillating element.
2. Brief Description of the Prior Art
The principle that the angular frequency of an oscillating mechanical system will change with a change in mass of the oscillating element is well known and has been used to determine mass.
Some of these mass measuring units utilize vibrating strings. These devices depend upon a frequency change in the vibrating string caused by a change in string tension. The tension is changed by increasing the weight pulling on the string. Thus, a change in weight can be determined by noting the change in the resonant frequency of the vibrating string.
The present invention oscillates the mass to be measured. Specific frequency of these oscillations is irrelevant to the measurement performed therein. Devices of this type which oscillate the mass to be measured however, operate at relatively high levels of damping and hence, accurate measurements cannot be made with these devices.
Some effort has been made in the past to reduce what are called "mounting" or "mechanical" losses caused by a transfer of energy from the vibrating system to the ground. The resultant devices have the oscillating member attached to a base which is not free to move relative to the oscillating member. This allows energy to be transmitted out of the oscillating element to the support structure whose own frequency characteristics directly effect the resonant condition of the measuring element.